Ecogas director Andrew Fisher says the new anaerobic digestion plant at Reporoa will make New Zealand’s clean green social licence more credible once it is up and running later this year.
New Zealand’s first-ever large-scale food waste-to-energy converter is on track to be ready for commissioning in August ahead of its official opening on October 17.
The facility at Reporoa, northeast of Taupō, will process 75,000 tonnes of waste a year and is consented to process 100,000 tonnes. It will convert the waste into methane for the national electricity grid, carbon dioxide for the food industry and liquid fertiliser for primary production.
The facility is owned by Ecogas, a joint venture between Pioneer Energy and Eco Stock Supplies and sits on land owned by T&G Fresh.
The plant can take food waste from curbside collections, food processing in meat, dairy and horticulture industries, as well as restaurant waste and cool store rejects.
It can also dispose of dairy farm effluent. If a district had a sudden weather event which threatened to overflow effluent ponds, it could take that liquid waste and prevent it from entering waterways.
Ecogas director Andrew Fisher said the plant will be a catalyst to allow food production and manufacturing to grow.
“This site here, if we can get it right, allows for a lot of the incumbent primary producers to expand their operations without having to expand their wastewater. They can put their capital into growing their productive elements,” Fisher said.
For companies shifting large quantities of food exports, it gave brand security and surety and gave them a place to dispose of a product in a sustainable way rather than risk it going into the market, he said.
“If you’re an exporter and going overseas, your audits are on your water and your environmental [footprint] if you can tell them it’s going here, this is what the world expects,” he said.
It also gave local government more peace of mind knowing that industries had that option of where to send their waste. It will help the country deal with some of its 327,000 annual tonnes of food waste, currently going into landfills.
The facility will service customers from as far south as Wellington, Palmerston North, Hawke’s Bay, Taranaki, Hamilton, Bay of Plenty, Gisborne and Auckland.
Those customers include 140 food manufacturers from the restaurant and food production industries who will use the facility.
Fisher said he has had good conversations with meat and dairy companies, including members of Fonterra’s sustainability team and Silver Fern Farms.
Ecogas is also working with trucking companies to ensure the waste being shipped to the processing facility is being done as efficiently as possible to reduce the carbon emissions of the transportation.
If the facility proves to be as successful as he hopes, he wants to build a second plant in Canterbury. Further into the future, he can see at least five to six facilities placed around the country.
Food waste comes into the facility and is stored in a large bunker. It is fed into a machine that separates the food from any plastic, with the food converted into a thick slurry-like substance.
The plastic is separated and baled and sent to Auckland, where it is converted to eco-rock, a substance that is being developed to use in concrete for the construction industry.
Any compostable packaging is also separated for commercial composting.
The slurry is degritted and pumped into a hydrolysis tank for two to three days.
From there, the product is put into one of the large digester tanks for 40 days. After that, it is and is pumped into a tank for pasteurisation.
Any solids left from the process are taken to a worm farm, while the liquid, which by now resembles a black tea, is made available as liquid fertiliser.
The gas generated from the process is 60% methane and 39% CO2. It is separated and cleaned with the CO2 bottled and sold to companies.
The methane is transferred to a generator to run the factory while excess gas, which is over 50% of the total gas produced, goes to the nearby gas line to be part of the national grid.
Liquid waste, such as dairy and meat processing wastewater, effluent and wastewater from cleaning the bunker and the factory floor, is collected and processed in a similar manner. It is pumped through a degritting system before entering the hydrolysis tank.
Fisher said it will change the way NZ deals with the environment and gives credibility to the country’s ‘clean green’ social licence.
“This is about extracting the last bits of value out of the food chain and also retaining some dignity into our food waste. It’s okay that we reject a product or that we have got cow manure, or that we have a failed export that did not meet export quality standards,” he said.
“It’s not going to go to a landfill and contribute to a problem, it’s going to go to another place and be a resource and contribute to further use.”
